Keratin, type I cytoskeletal 19 (K19)

Keratin, type I cytoskeletal 19 (K19), is the smallest member of the type I keratin (acidic) family and a structural protein forming part of the cytoskeleton in epithelial cells[2][7]. K19 is involved in maintaining structural integrity in epithelia and plays roles in linking myofiber structures in striated muscle and in stabilizing cell-cell adhesion[6][7]. K19 is widely expressed in various tissues, especially regions of labile or variable differentiation, and is implicated in supporting differentiational flexibility[3]. K19 is frequently used as a diagnostic and prognostic marker in multiple epithelial-origin cancers, with high K19 expression generally correlating with poor prognosis[1][2][7]. Recent research highlights regulatory roles in the cell cycle (Rb/E2F1 pathway), especially in cancer cell proliferation, but it is not a canonical therapeutic target with direct small-molecule or biologic inhibitors in current clinical use[1].

Other names

Keratin 19KRT19Cytokeratin 19CK19K1C19

Not a classical direct drug target; mechanisms relate to modulation of sensitivity to cell cycle inhibitors through interaction with cyclin D3, CDKs, and the Rb/E2F1 pathway[1]